1. Technical Field
The present invention relates to a robot control method, a robot control device, a robot, and a robot system.
2. Related Art
In recent years, the following has been known as a method of controlling a suction type robot (see JP-A-2010-69542). A robot hand is first made to move forward to a workpiece holding target position and a holding state is checked. When the holding state is not good, the workpiece holding target position is changed and the robot hand is made to move forward up to the holding state. When the holding state is good, the robot hand is made to move backward so as to take out a workpiece and the holding state is checked again. When the holding state is not good, the workpiece holding target position is changed and the robot hand is made to move again to the changed workpiece holding target position.
However, in the above-mentioned control method, the holding state when a workpiece has been held is checked, but when an external force is applied such as when the workpiece collides with something during work, when an inertial force is applied to the workpiece due to acceleration or deceleration, when the weight of the workpiece increases by attaching another component thereto, or when the workpiece is pressed against another component to attach the component thereto, there is a problem in that slipping occurs on the contact surface of the robot hand and the workpiece and thus the workpiece does not continued to be stably held, such that the holding is not continued or the holding position is changed.